Everything went wrong for AEK, who suffered a 3-0 defeat in Vallecas against Rayo and now face an uphill battle to qualify for the semi-finals ahead of the second leg next Thursday in Nea Filadelfia.
AEK missed 4 big chances in the first half, and cheap defensive errors cost them two goals in the 2nd minute by Acomas and in the 45'+2' by Lopez.
AEK started the second half determined to reduce the deficit and get back into the game, but a penalty from Palazon in the 74th minute made it 3-0.
AEK hit the post through Varga in the first half's significant moments, while Mantalos left with an injury. Jovic received a card and will miss the second leg.